We’ve all watched dozens of Disney movies where good outweighs bad. No matter how evil the villain was, Mulan, Cinderella, or Ariel always won.

Unfortunately, this Disney principle doesn’t carry over to our professional lives. Actually, it seems like it’s the opposite—no matter how many good, superstar employees you have, one toxic employee can bring everyone down. One rotten apple really can spoil the whole bunch.

A negative, nasty employee can ruin relationships with colleagues, customers, and managers. He or she can cause tension or conflict in the entire organization, and in the worst cases, prompt superstar employees to quit. It’s not easy confronting a toxic employee, but the sooner you do, the better your chances are of salvaging your culture.

The hard truth is that almost every organization has a toxic employee, and the first step is to recognize the signs. Some symptoms are: someone who has a negative attitude, who frequently has fights with colleagues, and who is never willing to go the extra mile to complete a project or help a coworker.

Once you’ve identified the bad apple, here are four steps to deal with the employee and save your organizational culture:

Open communication: Try to understand the root of the negativity. Talk to the toxic employee one-on-one, in a non-threatening manner. Your goal here is to gather information and hear the employee’s point of view. How does the employee feel about his or her work experience? How are things at home? Offer support if you identify a problem.

Talk to others: Sit down with employees who interact with this bad apple. How is the employee in question affecting their morale and job satisfaction? What are they experiencing on a daily basis? What would they like to see happen? Ask questions and record these anecdotes to understand the big picture.

Set a timeline: Assuming you have correctly identified the employee as toxic, go back and set clear expectations. Articulate which behaviors need to stop immediately and what you expect going forward. Provide a timeline for these changes—we recommend saying, “We’ll meet again in one month to discuss how you’re doing on these changes. I expect X, Y, and Z to improve by then.”

Reevaluate your options: Let’s say it’s been a month, and your bad apple hasn’t made any progress. At this point, you may need to consider something more drastic. Do you need to make a pay cut? Move him or her to a different department? Or is it time to terminate the bad apple? Firing someone should not be taken lightly, however if it’s the right thing to do, do it fast to avoid contaminating the entire organization.

Building a positive, healthy organizational culture takes time and effort. It is a fragile balancing act of people, interactions, and attitude, and one toxic employee could crumble everything you have tried so hard to build. Always be on the lookout for negativity in your office and act fast to maintain your company culture.